Contacts: Update Contact

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true), so the description's job is to add context. It does: the required auth header (`api-access-token`), the extra_body escape hatch, and the non-obvious encoding behavior (Persian/Arabic-Indic digits accepted and passed through unchanged). It still doesn't state whether omitted fields are left untouched (partial vs replace semantics).

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Four tightly packed sentences, purpose front-loaded, no repetition of the schema's per-field descriptions. Minor noise from the '[Contacts]' tag and the raw endpoint/auth boilerplate, but nothing wasteful enough to hurt.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 10-parameter REST mutation with no output schema, the description covers the essentials: identity, endpoint, auth, body field set, extension field, and encoding caveats. The one real gap is update semantics (partial vs full overwrite) and error behavior, which annotations only partially imply via idempotentHint.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description earns above baseline by documenting the extra_body merge mechanism and, more usefully, clarifying the accepted digit forms for ID/number-style parameters that the schema does not mention.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Update a contact by ID') and pins it to the exact endpoint PUT /api/v1/accounts/{account_id}/contacts/{id}. It is clearly separable from create/get/delete contact siblings, though it never explicitly distinguishes itself from the client-API twin gapify_client_update_contact beyond the auth line.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description says what the tool does but never when to use it versus alternatives (e.g. gapify_client_update_contact, gapify_create_contact, gapify_set_contact_labels). No preconditions, no exclusions, no routing guidance for the ~100 sibling tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.